BoilerFaultCodesYour boiler has detected that the water pressure inside the system is too low to run safely and has switched itself off.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Low Water Pressure
What causes this fault?
This fault occurs when the internal water pressure drops below the minimum level required for the boiler to operate safely. The most common reasons are a slow leak somewhere in your central heating pipework or radiators, or a loss of air pressure within the expansion vessel which is meant to regulate the system. In some cases, it can also happen if you have recently bled your radiators without topping the water level back up using the filling loop.
This issue is frequently seen at the start of autumn when homeowners turn their heating back on for the first time after summer, as stagnant pipes can reveal slow-release leaks or pressure drops.
DIY fix possible
Locate the filling loop (usually blue-handled levers) underneath the boiler.Slowly open the valves until you hear water entering the system.Watch the pressure gauge and close the valves when the needle reaches 1.5 bar.Restart the boiler if it does not reset automatically.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like 4.5 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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